Setting up a suppressed ringing connection to access customer premises equipment (CPE) entails accessing the CPE by suppressing the normal alerting signal to the customer so that the customer is not induced to try to answer the call. Typically, normal terminating features for the customer, such as call forwarding and call waiting, are bypassed for this suppressed ringing connection. The suppressed ringing connection typically uses frequency shift keying (FSK) or tone signals to perform an alerting function for the analog or digital customer premises equipment with which it may communicate in either the off-hook or on-hook mode. Communication can be initiated by a server, or the CPE can respond to the server. The communication takes place without disturbing the customer or being affected by customer features, over the same loop that is used for customer telephone conversations.
Trunks are preferably special purpose trunks, such as utility telemetry trunks, which are capable of establishing suppressed ringing connections over the public switched telephone network with a CPE. Trunks are useful for digital or analog communication.
After determining how many lines are available for a connection, the server initiates a suppressed ringing connection to the additional lines. Preferably, a no ring access is made to a CPE regardless of the features assigned to the line. For example, a connection is made to the user's line in spite of call forwarding features, call blocking features, or vacation service. The suppressed ringing connection is preferably indicated to the telephone network implicitly based on the trunk employed by the server to place the call, or alternately based on an indication made during call set up. To initiate the calls over a special trunk for suppressed ringing, the server goes off-hook and seizes the suppressed ringing trunk and outpulses the required set-up data, including a destination number and optional billing number. If the user's line is not busy, a connection is cut through. Once the server receives acknowledgement from the switch that the connection is cut through, the customer premises equipment is alerted, for example by a frequency shift keying data stream, a single or dual tone, or other alerting method.
In current suppressed ringing connections, a call path is set up and maintained between the server and the CPE. This consumes switch resources, while only using the actual customer line for short periods of time. There is a need to minimize switch resources when a telemetry call is placed to a CPE.
Therefore, a need exists for a method and apparatus that is able to communicate information with customer premises equipment without alerting the user, without setting up a call path to the customer premises equipment, and that is not affected by features of the line to which customer premises equipment is connected.